1. Technical Field
The present invention relates to switched communications networks providing voice mail services, more particularly to a system and method for providing voice mail services to telephone subscribers having ported numbers assigned from one central office to a new central office.
2. Background Art
Voice mail has become commonplace not only in business usage but also on an individual telephone service subscriber basis through service from a central office. A voice mail system is a specialized computer that stores messages in digital form on a disk. The voice is generally digitized, usually at a much slower rate than the 64 Kb/s signal the central office uses in its switching network. The digitized voice is compressed and stored on a hard disk that maintains the voice mail operating system, system prompts, and greetings, and the messages themselves. A processor controls the compressing, storing, retrieving, forwarding and purging of files. A comprehensive review of exemplary voice mail systems and voice messaging systems is disclosed in U.S. Pat. No. 5,631,948 to Bartholomew et al., the disclosure of which is incorporated in its entirety herein by reference.
FIG. 1 is a block diagram illustrating an exemplary voice mail implementing communication system, corresponding to FIG. 5 of the above-incorporated Bartholomew et al. patent. As shown in FIG. 1, at least one switching system 10 is connected to a centralized message service voice mail 20. The switching system 10 may be a local or xe2x80x9cend officexe2x80x9d type telephone central office switch, such as a 1AESS or 5ESS switch sold by American Telephone and Telegraph.
Structurally, the switching system 10 is a standard central office telephone switch. Each subscriber has at least one piece of customer premises equipment, illustrated as telephone station sets 31 to 33. Local telephone lines 35 to 37 serve as communication links between each of the telephone station sets 31 to 33 and the end office switching system 10. The subscriber station equipment can comprise any communication device compatible with the line. Where the line is a standard voice grade telephone line, for example, the subscriber station equipment could include facsimile devices, modems etc.
The centralized message service or voice mail system in FIG. 1 comprises voice messaging equipment such as a voice mail system 20. Although referred to as xe2x80x9cvoicexe2x80x9d messaging equipment, equipment 20 may have the capability of storing messages of a variety of different types as well as voice messages. For example, a single system 20 may receive incoming messages in the form of audible messages, such as voice messages, as well as text format data messages, image data format (e.g., facsimile) messages, etc. Message service systems having the capability to store messages in a variety of audible, data and image formats are known, see e.g. U.S. Pat. No. 5,193,110 to Jones et al., U.S. Pat. No. 5,008,926 to Misholi and U.S. Pat. No. 4,652,700 to Matthews et al.
The illustrated voice mail system 20 includes a digital switching system (DSS) 21, a master control unit (MCU) 23, a number of voice processing units (VPU""s) 25 and a master interface unit (MIU) or concentrator 27. The master control unit (MCU) 23 of the voice mail system 20 is a personal computer type device programmed to control overall operations of the system 20.
Each of the voice processing units 25 includes or connects to one or more digital mass storage type memory units (not shown) in which the actual messages are stored. The mass storage units, for example, may comprise magnetic disc type memory devices. Although not specifically illustrated in the drawing, the voice processing units 25 also include appropriate circuitry to transmit and receive audio signals via T1 type digital audio lines. To adapt the system 20 to receive information other than voice and/or offer services other than voice mail, one or more of VPU""s 25 might be reprogrammed to run other types of applications and/or process other types of incoming information. For example, one such unit might process facsimile information, one might process E-mail, etc.
An ETHERNET type digital network 29 carries data signals between the MCU 23 and the voice processing units 25. The Ethernet network 29 also carries stored messages, in digital data form, between the various voice processing units 25. The system 20 further includes T1 type digitized audio links 28 between the DSS switch 21 and each of the voice processing units 25.
The voice mail system 20 connects to the switching system 10 via a number of simplified message desk interface (SMDI) type data lines 41. Specifically, these SMDI links 41 connect between one or more data units (not shown) in the end office switching system 10 and the MIU 27. Each SMDI line 41 carries 2400 baud RS-232 data signals in both directions between the voice mail system 20 and the switching system 10. The MIU 27 is a data concentrator which effectively provides a single connection of as many as thirty-two SMDI lines into the MCU 23 of the voice mail system.
The voice mail system 20 also connects to the end office switching system 10 via a number of voice lines 43 which form a multi-line hunt group (MLHG) between the switch matrix within the switching system 10 and the DSS switch 21 of the voice mail system 20. Typically, the MLHG lines 43 consist of a number of T1 type trunk circuits which each carry 24 voice channels in digital time division multiplexed format.
Calls can be forwarded to the voice mail system 20 in response to calls to subscriber""s lines served by the end office switching system 10. When the end office switching system 10 forwards a call to the voice mail system 20, the switching system 10 will also provide various data relating to the call via one of the SMDI links 41 and the MIU 27. In particular, the switching system 10 transmits data to the MCU 23 of the voice mail system 20 indicating which line of the multi-line hunt group 43, i.e. which T1 trunk and which channel on the trunk, that the new call will come in on. The exchange 10 also transmits data via SMDI link 41 identifying the called telephone number and the telephone number of the caller. For a call forwarded to a mailbox, the data from the exchange indicates the reason for the forwarding, and the caller telephone number (typically the directory number assigned to the called subscriber""s normal telephone line) identifies which subscriber the forwarded call relates to. The master control unit 23 uses the multi-line hunt group line information and the subscriber""s directory number to internally route the forwarded call though DSS switch 21 and one of the internal T1 links 28 to an available voice processing unit 25 and identifies the relevant subscriber to that voice processing unit via the Ethernet 25.
For each party who subscribes to a voice mail service provided by the centralized messaging system 20, the MCU 23 stores information designating one of the voice processing units 25 as the xe2x80x9chomexe2x80x9d unit for that subscriber. Each voice processing unit 25 stores generic elements of prompt messages in a common area of its memory. Personalized elements of prompt messages, for example recorded representations of each subscriber""s name spoken in the subscriber""s own voice, are stored in designated memory locations within the subscriber""s xe2x80x9chomexe2x80x9d voice processing unit.
Hence, the voice mail messaging system 20 is configured for receiving forwarded telephone calls for a called party (e.g., subscriber 31) having subscriber profile information stored in the end office switching system 10. Hence, upon detecting a no answer/busy condition on the corresponding line 37, the end office switching system can forward the incoming call to the MLHG 43 and supply the appropriate information associated with the called party across the SMDI link 41 to internally route the forwarded call to the assigned voice processing unit 25 and to identify the relevant subscriber to the voice processing unit 25.
The above-described voice mail systems operate on the assumption that the subscriber is served by an end office switching system 10 having dedicated MLHG 43 and SMDI 41 connections to the voice mail systems 20. Consequently, each SMDI link 41 for an associated end office switching system is assigned a preprovisioned range of exchange codes corresponding to at least a portion of the exchange codes assigned to the end office switching system according to the North American Number Plan (NANP). Hence, if the switching system 10 is assigned the exchange codes 500, 501, 502, 503, 504, the corresponding SMDI link 41 will be provisioned to recognize only those exchange codes (500, 501, 502, 503, and 504) from the end office switching system as valid, identifiable subscribers. The provisioning of a predetermined range of exchanges for the SMDI link 41 enables the MCU 23 to properly identify a subscriber (and appropriate VPU 25) based on the called number information from the SMDI link 41.
The Federal Communications Commission has issued a xe2x80x9cFIRST REPORT AND ORDER AND FURTHER NOTICE OF PROPOSED RULEMAKINGxe2x80x9d document (referred to hereinafter as the FCC document) that contains a description of proposed telephone number portability methods. Number Portability relates to the ability of a telephone service subscriber to select or change the selection of a carrier for providing that customer""s local telephone service, while still maintaining the subscriber""s telephone number at the same customer premises.
FIG. 2 illustrates a telephone network wherein a customer at station 12 may obtain local exchange telephone service from either a local exchange carrier (LEC) or a competing local exchange carrier (CLEC). In the illustrated example, the customer at station 12, who originally received telephone and voice mail services through the LEC end office 10 and a connected voice mail system 20, has now selected the competing carrier for local service. Accordingly, the station 12 now connects to the CLEC end office 14.
As described above, the voice mail system 20 was configured to identify the called party 12 based on information forwarded by the EO 10 across the SMDI link 41. Assuming the customer at station 12 had a telephone number (703) 502-1234, the SMDI link 41 is provisioned to recognize the 703-502 prefix from the EO 10. However if the station is now connected to the CLEC EO 14 having a 703-999 exchange, then no useful called party information for the station 12 at (703) 502-1234 could be provided by the CLEC EO 14 to the VMS 20.
For example, assume station 1 at EO 17 wanted to call station 12 at (703) 502-1234. After performing a database lookup to identify the CLEC EO 14 as the serving end office, the EO 17 would attempt a call to the EO 14, for example via a tandem office 24. Subscriber profile information within the CLEC EO 14 would cause the CLEC EO 14 to perform a call forwarding function to the VMS 20 upon detecting a busy/no answer condition. A call forwarding on busy/no answer by the CLEC EO 14 to the MLHG 43 via EO 10 would identify MLHG telephone number (703) 502-0000 as the called party via the SMDI link, since the EO 10 would interpret the incoming call from the CLEC EO 14 call as a generic call to the voice mail system. Hence, the generic call to the VMS 20 would require a calling party at station 1 to re-input the called party information.
Moreover, no called party information for the station 12 at (703) 502-1234 could be interpreted by the VMS 20 even if the CLEC EO 14 had its own dedicated SMDI connection to the VMS 20. Assuming the CLEC EO 14 had its own dedicated SMDI connection to the VMS 20, that dedicated SMDI connection would be provisioned with a different predetermined range of exchanges served by the CLEC EO 14 (e.g., 997, 998, 999). Hence, if the CLEC EO 14 forwarded an incoming call intended for station 12 at (703) 502-1234 to VMS 20 and supplied the called number across the dedicated SMDI link, the VMS 20 would be incapable of interpreting the called number (703) 502-XXXX, since called number prefix was not within the predetermined range of exchanges provisioned for the CLEC EO 14. Hence, the VMS 20, incapable of interpreting the 703-502 prefix from the CLEC EO 14 (serving 997, 998, and 999), would route the incoming call to a generic greeting, requiring the calling party to input the called party number.
There is a need for an arrangement that enables a subscriber to utilize telephone number portability features without compromising voice mail messaging features.
There is also a need for an arrangement that enables a voice mail system to receive called party information specifying a voice mail subscriber, having telephone number portability, from an end office that does not have the same provisioned prefix code assigned within the voice mail switch.
There is also a need for an arrangement that enables any end office to forward an incoming call to a personalized greeting in a voice mail system serving a corresponding voice mail subscriber having number portability services, independent of any preexisting prefix code ranges that may have been provisioned within the voice mail system.
There is a further need for an arrangement that enables a subscriber having voice mail services to switch to a competing local exchange carrier with a portable telephone number, without any disruption in voice mail services or features. Such voice mail features include automatic playback of personalized greetings for no answer/busy conditions without requiring a calling party to enter the called party number for identification of the voice mail subscriber by the voice mail system.
These and other needs are attained by the present invention, where a communications system providing number portability provides a signaling and messaging protocol enabling a voice mail system to receive signaling information identifying a called party, independent of the end office switching system serving the called party. The communications system uses a voice mail messaging system having interoffice voice messaging capabilities, where the voice mail messaging system is capable of receiving called party information across a data link interface according to a protocol that is independent of any predetermined range of provisioned exchanges. One exemplary voice mail data link interface is the commercially-available Premier Message Service Interface (PMSI), which enables a first central office serving a connected subscriber to forward a call to a second central office serving the voice mail system, without the necessity of a dedicated data link between the first central office and the voice mail system. Specifically, a voice mail system having a PMSI data link with a central office switching system is able to receive interoffice signaling information received by the central office switching system, independent of the prefix code of the forwarding central office switching system.
The present invention applies the features of PMSI-configured voice mail systems to provide a voice messaging system for messaging number portability, where individual subscribers can use personalized voice messaging services in conjunction with number portability. According to one aspect of the present invention, a communications system includes an originating central office switching system serving a calling station and that is configured to access a database to identify a network address for a serving central office switching system that provides telecommunications services for a called number identified as a ported telephone number. The database may be a localized database within the originating central office switching system, or a centralized database accessed in response to a trigger set in the originating central office switching system. The communications system also includes a voice mail system (VMS)-serving central office switching system that provides line-sided connections and signaling information to a voice mail system according to a prescribed protocol independent of any predetermined range of provisioned exchanges.
The calling station sends a first signaling message to the serving central office switching system, where the signaling message includes the network address of the serving central office switching system within a called number field of the signaling message, and the actual called number (i.e., the ported number) in a supplemental address parameter field. The calling station inserts the network address within the called number field, instead of the actual called number, to supply the first signaling message to the actual central office switching system serving the ported number.
The serving central office switching system, upon recognizing the first signaling message as a terminating attempt to a ported number, will determine availability or busy status of the actual destination station specified in the supplemental address parameter field. The serving central office switching system includes ported number forwarding logic for selectively generating a second signaling message to the VMS-serving central office switching system in response to detecting a condition relating to the ported number requiring forwarding to a voice mailbox serving the called party, for example a no answer/busy condition on the local communication line serving the ported telephone number. The ported number forwarding logic generates the second signaling message by setting the calling field to equal the ported number specified in the supplemental address field, to enable the destination voice mail system to appropriately identify the voice mail subscriber.
Hence, the ported number forwarding logic generates the signaling message to the VMS-serving central office switching system in a manner that enables the VMS-serving central office switching system to identify the voice mail subscriber, enabling playback of a personalized greeting for the calling party.
Another aspect of the present invention provides a communications system where the originating central office switching system includes the ported number forwarding logic to enable the originating central office switching system to directly access the voice mail system of the called party, independent of the capabilities of the central office switching system serving the ported number. The originating central office switching system sends the first signaling message to the serving central office switching system, as described above following a first database access, to determine the availability of the called party at the ported number.
If the originating central office switching system determines from the serving central office switching system that the called party at the ported number is busy, the originating central office switching system sends a second signaling message to the VMS-serving central office switching system based on a second network address from the database access. The second network address for the VMS-serving central office switching system may be obtained during the original database access, or by a second database access in response to detecting the no answer/busy condition. The originating central office switching system also initiates a line-sided connection with the VMS-serving central office switching system, enabling the voice mail system to provide a personalized greeting for the calling party based on the data supplied in the second signaling message.
Hence, the present invention provides an arrangement that enables efficient and economical implementation of voice mail services for subscribers having number portability services. Hence, voice mail subscribers may maintain their personalized voice mail services, independent of the porting of their telephone numbers to different central offices.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.